I seem to have both in my parts bin. The aluminum one on the left fits into a 7 inch globe ring on the pump and allows you to put a 6 inch base globe onto that pump. The red cast iron one, goes the opposite way. allows a globe with a 7 inch base to be installed on a pump with a 6 inch globe holder. You can have either for $100 and the shipping.
Everything Cities Service Specializing in old Gas Pumps firstname.lastname@example.org Cell#-701-739-6133